goog.module('grrUi.core.onScrollIntoViewDirective');
goog.module.declareLegacyNamespace();



/**
 * Controller for OnScrollIntoViewDirective.
 *
 * @constructor
 *
 * @param {!angular.Scope} $scope
 * @param {!angular.jQuery} $element
 * @param {!angular.Attributes} $attrs
 * @param {!angular.$interval} $interval
 * @param {!angular.$window} $window
 *
 * @ngInject
 */
const OnScrollIntoViewController = function(
    $scope, $element, $attrs, $interval, $window) {

  /** @private {!angular.Scope} */
  this.scope_ = $scope;

  /** @private {!angular.Attributes} */
  this.attrs_ = $attrs;

  /** @private {!angular.jQuery} */
  this.element_ = $element;

  /** @private {!angular.$window} */
  this.window_ = $window;

  /** @type {boolean} */
  this.currentlyVisible = false;

  var stop = $interval(this.onInterval.bind(this), 100);
  $scope.$on('$destroy', function() {
    $interval.cancel(stop);
  });
};

/**
 * Handles $interval events. Evaluates grr-on-scroll-into-view attribute
 * if element became visible.
 */
OnScrollIntoViewController.prototype.onInterval = function() {
  var elemOffset = $(this.element_).offset();
  var elemWidth = $(this.element_).width();
  var elemHeight = $(this.element_).height();

  var elem = document.elementFromPoint(
      elemOffset.left - $(this.window_).scrollLeft() + 1,
      elemOffset.top - $(this.window_).scrollTop() + 1);
  var isVisible = (elem == $(this.element_)[0]);

  if (!isVisible) {
    elem = document.elementFromPoint(
      elemOffset.left + elemWidth - $(this.window_).scrollLeft() - 1,
      elemOffset.top + elemHeight - $(this.window_).scrollTop() - 1);
    isVisible = (elem == $(this.element_)[0]);
  }

  if (!isVisible) {
    elem = document.elementFromPoint(
      elemOffset.left + elemWidth / 2 - $(this.window_).scrollLeft(),
      elemOffset.top + elemHeight / 2 - $(this.window_).scrollTop());
    isVisible = (elem == $(this.element_)[0]);
  }

  if (this.currentlyVisible != isVisible) {
    this.currentlyVisible = isVisible;
    if (isVisible) {
      this.scope_.$eval(this.attrs_['grrOnScrollIntoView']);
    }
  }
};

/**
 * Directive that triggers custom user action when element scrolls into view.
 *
 * @return {!angular.Directive} Directive definition object.
 * @ngInject
 * @export
 */
exports.OnScrollIntoViewDirective = function() {
  return {
    restrict: 'A',
    controller: OnScrollIntoViewController
  };
};


/**
 * Directive's name in Angular.
 *
 * @const
 * @export
 */
exports.OnScrollIntoViewDirective.directive_name = 'grrOnScrollIntoView';
